The present invention relates to an arrangement for opening and closing coverings for architectural openings such as Venetian blinds, pleated shades, cellular shades, and vertical blinds.
Typically, a transport system for a covering that extends and retracts in the vertical direction has a fixed head rail which both supports the covering and hides the mechanisms used to raise and lower or extend and retract the covering. Such a transport system is described in U.S. Pat. No. 6,536,503, Modular Transport System for Coverings for Architectural Openings, which is hereby incorporated herein by reference. In the typical horizontal covering product that moves downwardly from the top (top/down), the extension and retraction of the covering is done by lift cords or lift tapes suspended from the head rail and attached to the bottom rail (also referred to as the moving rail or bottom slat). In a Venetian blind, there are ladder tapes that support the slats, and the lift cords usually run through holes in the middle of the slats.
Raising and lowering the covering may be done by pulling directly on the lift cords or tapes or by operating a drive cord, which drives a mechanism inside a rail (usually a fixed head rail) that rotates a lift rod and lift spools to cause the lift cord or tape to wind and unwind. (It is understood that, when the phrase “lift cord” is used in this application, it also includes lift tapes.)
Some window covering products are built in the reverse (bottom-up), where the moving rail, instead of being at the bottom of the window covering bundle, is at the top of the window covering bundle, between the bundle and the head rail, such that the bundle is normally accumulated at the bottom of the window when the covering is retracted and the moving rail is at the top of the window covering, next to the head rail, when the covering is extended. There are also composite products which are able to do both, to go top-down and/or bottom-up.
Known cord drives have some drawbacks. For instance, the cords in a cord drive may be hard to reach when the cord is high up (and the blind is in the fully lowered position), or the cord may drag on the floor when the blind is in the fully raised position. The cord drive also may be difficult to use, requiring a large amount of force to be applied by the operator, or requiring complicated changes in direction in order to perform various functions such as locking or unlocking the drive cord.
It also has been found desirable to reduce or eliminate the amount of exposed cord.